This invention relates to the chemical arts. In particular, this invention relates to an improved method of making a cellular crosslinked polymer of dicyclopentadiene with a metathesis-catalyst system.
U.S. Pat. No. 4,002,815 discloses the use of a metathesis-catalyst system which employs a dialkylaluminum iodide, an alkylaluminum diiodide or a mixture of trialkylaluminum compounds with elemental iodine to produce substantially gel-free copolymers of cyclopentene and dicyclopentadiene.
U.S. application Ser. No. 526,835 filed Aug. 26, 1983 and assigned to the same assignee, discloses a cellular crosslinked poly(dicyclopentadiene) which is a made with a metathesis-catalyst system. The cellular polymer is made by injecting the catalyst system, which includes an alkylaluminum activator, into a reaction vessel which is preheated, preferably to a temperature from about 100.degree. C. to about 125.degree. C.
Now it has been found that the activation of a metathesis-catalyst with an alkylaluminum iodide compound results in a catalyst system capable of polymerizing dicyclopentadiene monomer into a cellular crosslinked polymer having good uniformity of structure without having to preheat the reaction vessel to high temperatures.